Author: bdelacretaz
Date: Wed Jul 30 13:23:12 2014
New Revision: 1614655
URL: http://svn.apache.org/r1614655
Log:
SLING-3744 - optionally schedule execution of health checks via cron-like
service property. Contributed by Georg Henzler, thanks!
Added:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/AsyncHealthCheckExecutor.java
Modified:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/api/HealthCheck.java
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckExecutorImpl.java
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckFuture.java
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/util/HealthCheckMetadata.java
sling/trunk/bundles/extensions/healthcheck/samples/pom.xml
sling/trunk/bundles/extensions/healthcheck/samples/src/main/java/org/apache/sling/hc/samples/impl/AsyncHealthCheckSample.java
sling/trunk/bundles/extensions/healthcheck/samples/src/main/resources/SLING-CONTENT/apps/hc/demo/install/org.apache.sling.hc.samples.impl.AsyncHealthCheckSample-1.json
Modified:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/api/HealthCheck.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/api/HealthCheck.java?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/api/HealthCheck.java
(original)
+++
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/api/HealthCheck.java
Wed Jul 30 13:23:12 2014
@@ -60,7 +60,13 @@ public interface HealthCheck {
* The value of this property must be of type String or String array.
*/
String TAGS = "hc.tags";
-
+
+ /**
+ * Optional service property: If this property is set the health check
+ * will be executed asynchronously using the cron expression provided.
+ */
+ String ASYNC_CRON_EXPRESSION = "hc.async.cronExpression";
+
/**
* Execute this health check and return a {@link Result}
* This is meant to execute quickly, access to external
Added:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/AsyncHealthCheckExecutor.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/AsyncHealthCheckExecutor.java?rev=1614655&view=auto
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/AsyncHealthCheckExecutor.java
(added)
+++
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/AsyncHealthCheckExecutor.java
Wed Jul 30 13:23:12 2014
@@ -0,0 +1,246 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The SF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+package org.apache.sling.hc.core.impl.executor;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.apache.commons.lang.StringUtils;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.Service;
+import org.apache.sling.commons.scheduler.Scheduler;
+import org.apache.sling.hc.api.HealthCheck;
+import org.apache.sling.hc.api.Result;
+import org.apache.sling.hc.api.execution.HealthCheckExecutionResult;
+import org.apache.sling.hc.core.impl.executor.HealthCheckFuture.Callback;
+import org.apache.sling.hc.util.HealthCheckFilter;
+import org.apache.sling.hc.util.HealthCheckMetadata;
+import org.osgi.framework.BundleContext;
+import org.osgi.framework.ServiceEvent;
+import org.osgi.framework.ServiceListener;
+import org.osgi.framework.ServiceReference;
+import org.osgi.service.component.ComponentContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Runs health checks that are configured with a cron expression for
asynchronous
+ * execution. Used by HealthCheckExecutor.
+ *
+ */
+@Service({ AsyncHealthCheckExecutor.class })
+@Component(label = "Sling Async Health Check Executor",
+ description = "Runs async health checks",
+ metatype = true, immediate = true)
+public class AsyncHealthCheckExecutor implements ServiceListener {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(AsyncHealthCheckExecutor.class);
+
+ @Reference
+ private Scheduler scheduler;
+
+ private Map<HealthCheckMetadata, ExecutionResult> asyncResultsByDescriptor
= new ConcurrentHashMap<HealthCheckMetadata, ExecutionResult>();
+
+ private Map<HealthCheckMetadata, HealthCheckAsyncJob> registeredJobs = new
HashMap<HealthCheckMetadata, HealthCheckAsyncJob>();
+
+ private BundleContext bundleContext;
+
+
+
+ @Activate
+ protected final void activate(final ComponentContext componentContext) {
+ this.bundleContext = componentContext.getBundleContext();
+ this.bundleContext.addServiceListener(this);
+
+ int count = 0;
+ HealthCheckFilter healthCheckFilter = new
HealthCheckFilter(bundleContext);
+ final ServiceReference[] healthCheckReferences =
healthCheckFilter.getTaggedHealthCheckServiceReferences(new String[0]);
+ for (ServiceReference serviceReference : healthCheckReferences) {
+ HealthCheckMetadata healthCheckMetadata = new
HealthCheckMetadata(serviceReference);
+ if (isAsync(healthCheckMetadata)) {
+ if (scheduleHealthCheck(healthCheckMetadata)) {
+ count++;
+ }
+ }
+ }
+ LOG.debug("Scheduled {} jobs for asynchronous health checks", count);
+ }
+
+ @Deactivate
+ protected final void deactivate(final ComponentContext componentContext) {
+ this.bundleContext.removeServiceListener(this);
+ this.bundleContext = null;
+
+ LOG.debug("Unscheduling {} jobs for asynchronous health checks",
registeredJobs.size());
+ for (HealthCheckMetadata healthCheckDescriptor : new
LinkedList<HealthCheckMetadata>(registeredJobs.keySet())) {
+ unscheduleHealthCheck(healthCheckDescriptor);
+ }
+
+ }
+
+ @Override
+ public void serviceChanged(ServiceEvent event) {
+ if(bundleContext == null) {
+ // already deactivated?
+ return;
+ }
+ ServiceReference serviceReference = event.getServiceReference();
+ final boolean isHealthCheck =
serviceReference.isAssignableTo(bundleContext.getBundle(),
HealthCheck.class.getName());
+
+ if (isHealthCheck) {
+ HealthCheckMetadata healthCheckMetadata = new
HealthCheckMetadata(serviceReference);
+ int eventType = event.getType();
+ LOG.debug("Received service event of type {} for health check {}",
eventType, healthCheckMetadata);
+ if (eventType == ServiceEvent.REGISTERED) {
+ scheduleHealthCheck(healthCheckMetadata);
+ } else if (eventType == ServiceEvent.UNREGISTERING) {
+ unscheduleHealthCheck(healthCheckMetadata);
+ } else if (eventType == ServiceEvent.MODIFIED) {
+ unscheduleHealthCheck(healthCheckMetadata);
+ scheduleHealthCheck(healthCheckMetadata);
+ }
+
+ }
+ }
+
+ private boolean scheduleHealthCheck(HealthCheckMetadata descriptor) {
+
+ if(!isAsync(descriptor)) {
+ return false;
+ }
+
+ try {
+ HealthCheckAsyncJob healthCheckAsyncJob = new
HealthCheckAsyncJob(descriptor);
+ LOG.debug("Scheduling job {} with cron expression {}",
healthCheckAsyncJob, descriptor.getAsyncCronExpression());
+ this.scheduler.addJob(healthCheckAsyncJob.getJobId(),
healthCheckAsyncJob, null, descriptor.getAsyncCronExpression(), true);
+ registeredJobs.put(descriptor, healthCheckAsyncJob);
+ return true;
+ } catch (Exception e) {
+ LOG.warn("Could not schedule job for " + descriptor + ".
Exeception: " + e, e);
+ return false;
+ }
+
+ }
+
+ private boolean unscheduleHealthCheck(HealthCheckMetadata descriptor) {
+
+ // here no check for isAsync must be used to ensure previously
+ // scheduled async checks are correctly unscheduled if they have
+ // changed from async to sync.
+
+ HealthCheckAsyncJob job = registeredJobs.remove(descriptor);
+ try {
+ if (job != null) {
+ LOG.debug("Unscheduling job {} with cron expression '{}'",
job, descriptor.getAsyncCronExpression());
+ this.scheduler.removeJob(job.getJobId());
+ return true;
+ }
+ } catch (Exception e) {
+ LOG.warn("Could not unschedule job " + job + ". Exeception: " + e,
e);
+ }
+ return false;
+
+ }
+
+ void collectAsyncResults(List<HealthCheckMetadata> healthCheckDescriptors,
Collection<HealthCheckExecutionResult> results) {
+ Iterator<HealthCheckMetadata> checksIt =
healthCheckDescriptors.iterator();
+
+ Set<ExecutionResult> asyncResults = new TreeSet<ExecutionResult>();
+ while (checksIt.hasNext()) {
+ HealthCheckMetadata healthCheckMetadata = checksIt.next();
+ if (isAsync(healthCheckMetadata)) {
+ ExecutionResult result =
asyncResultsByDescriptor.get(healthCheckMetadata);
+ if (result == null) {
+
+ result = new ExecutionResult(healthCheckMetadata, new
Result(Result.Status.INFO, "Async Health Check with cron expression '"
+ + healthCheckMetadata.getAsyncCronExpression() +
"' has not yet been executed."), 0L);
+
+ asyncResults.add(result);
+ }
+ asyncResults.add(result);
+ // remove from HC collection to not execute the check in
HealthCheckExecutorImpl
+ checksIt.remove();
+ }
+ }
+ LOG.debug("Adding {} results from async results", asyncResults.size());
+ results.addAll(asyncResults);
+
+ }
+
+ private boolean isAsync(HealthCheckMetadata healthCheckMetadata) {
+ return
StringUtils.isNotBlank(healthCheckMetadata.getAsyncCronExpression());
+ }
+
+
+ private class HealthCheckAsyncJob implements Runnable {
+
+ private final HealthCheckMetadata healthCheckDescriptor;
+
+ public HealthCheckAsyncJob(HealthCheckMetadata healthCheckDescriptor) {
+ super();
+ this.healthCheckDescriptor = healthCheckDescriptor;
+ }
+
+ public String getJobId() {
+ String jobId = "job-hc-" + healthCheckDescriptor.getServiceId();
+ return jobId;
+ }
+
+ @Override
+ public void run() {
+
+ LOG.debug("Running job {}", this);
+ HealthCheckFuture healthCheckFuture = new
HealthCheckFuture(healthCheckDescriptor, bundleContext, new Callback() {
+
+ @Override
+ public void finished(HealthCheckExecutionResult result) {
+ // no action needed here
+
+ }});
+
+ // run future in same thread (as we are already async via
scheduler)
+ healthCheckFuture.run();
+
+ try {
+ ExecutionResult result = healthCheckFuture.get();
+ LOG.debug("Aync execution of {} returned {}",
healthCheckDescriptor, result);
+ asyncResultsByDescriptor.put(healthCheckDescriptor, result);
+ } catch (Exception e) {
+ LOG.warn("Could not upated async execution result for " +
healthCheckDescriptor + ". Exception: " + e, e);
+ }
+
+ }
+
+ @Override
+ public String toString() {
+ return "[Async job for " + this.healthCheckDescriptor + "]";
+ }
+
+ }
+
+}
Modified:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckExecutorImpl.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckExecutorImpl.java?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckExecutorImpl.java
(original)
+++
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckExecutorImpl.java
Wed Jul 30 13:23:12 2014
@@ -103,6 +103,9 @@ public class HealthCheckExecutorImpl imp
private final Map<HealthCheckMetadata, HealthCheckFuture>
stillRunningFutures = new HashMap<HealthCheckMetadata, HealthCheckFuture>();
@Reference
+ private AsyncHealthCheckExecutor asyncHealthCheckExecutor;
+
+ @Reference
private ThreadPoolManager threadPoolManager;
private ThreadPool hcThreadPool;
@@ -199,6 +202,7 @@ public class HealthCheckExecutorImpl imp
final List<HealthCheckExecutionResult> results = new
ArrayList<HealthCheckExecutionResult>();
final List<HealthCheckMetadata> healthCheckDescriptors =
getHealthCheckMetadata(healthCheckReferences);
+
createResultsForDescriptors(healthCheckDescriptors, results);
stopWatch.stop();
@@ -223,6 +227,9 @@ public class HealthCheckExecutorImpl imp
// -- All methods below check if they can transform a
healthCheckDescriptor into a result
// -- if yes the descriptor is removed from the list and the result
added
+ // get async results
+ asyncHealthCheckExecutor.collectAsyncResults(healthCheckDescriptors,
results);
+
// reuse cached results where possible
healthCheckResultCache.useValidCacheResults(healthCheckDescriptors,
results, resultCacheTtlInMs);
Modified:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckFuture.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckFuture.java?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckFuture.java
(original)
+++
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/core/impl/executor/HealthCheckFuture.java
Wed Jul 30 13:23:12 2014
@@ -21,7 +21,6 @@ import java.util.Date;
import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;
-import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.time.StopWatch;
import org.apache.sling.hc.api.HealthCheck;
import org.apache.sling.hc.api.Result;
@@ -50,8 +49,7 @@ class HealthCheckFuture extends FutureTa
super(new Callable<ExecutionResult>() {
@Override
public ExecutionResult call() throws Exception {
- Thread.currentThread().setName(
- "Health-Check-" +
StringUtils.substringAfterLast(metadata.getTitle(), "."));
+ Thread.currentThread().setName("HealthCheck " +
metadata.getTitle());
LOG.debug("Starting check {}", metadata);
final StopWatch stopWatch = new StopWatch();
@@ -84,8 +82,8 @@ class HealthCheckFuture extends FutureTa
LOG.debug("Time consumed for {}: {}", metadata,
HealthCheckExecutorImpl.msHumanReadable(elapsedTime));
}
- Thread.currentThread().setName("Health-Check-idle");
callback.finished(executionResult);
+ Thread.currentThread().setName("HealthCheck idle");
return executionResult;
}
});
Modified:
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/util/HealthCheckMetadata.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/util/HealthCheckMetadata.java?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/util/HealthCheckMetadata.java
(original)
+++
sling/trunk/bundles/extensions/healthcheck/core/src/main/java/org/apache/sling/hc/util/HealthCheckMetadata.java
Wed Jul 30 13:23:12 2014
@@ -41,6 +41,8 @@ public class HealthCheckMetadata {
private final long serviceId;
private final List<String> tags;
+
+ private final String asyncCronExpression;
private final transient ServiceReference serviceReference;
@@ -50,6 +52,7 @@ public class HealthCheckMetadata {
this.mbeanName = (String) ref.getProperty(HealthCheck.MBEAN_NAME);
this.title = getHealthCheckTitle(ref);
this.tags =
arrayPropertyToListOfStr(ref.getProperty(HealthCheck.TAGS));
+ this.asyncCronExpression = (String)
ref.getProperty(HealthCheck.ASYNC_CRON_EXPRESSION);
this.serviceReference = ref;
}
@@ -89,6 +92,14 @@ public class HealthCheckMetadata {
public List<String> getTags() {
return tags;
}
+
+
+ /**
+ * Return the cron expression used for asynchronous execution.
+ */
+ public String getAsyncCronExpression() {
+ return asyncCronExpression;
+ }
/**
* Return the service id.
Modified: sling/trunk/bundles/extensions/healthcheck/samples/pom.xml
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/samples/pom.xml?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
--- sling/trunk/bundles/extensions/healthcheck/samples/pom.xml (original)
+++ sling/trunk/bundles/extensions/healthcheck/samples/pom.xml Wed Jul 30
13:23:12 2014
@@ -85,7 +85,7 @@
<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.hc.core</artifactId>
- <version>1.0.4</version>
+ <version>1.1.1-SNAPSHOT</version>
<scope>provided</scope>
</dependency>
<dependency>
Modified:
sling/trunk/bundles/extensions/healthcheck/samples/src/main/java/org/apache/sling/hc/samples/impl/AsyncHealthCheckSample.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/samples/src/main/java/org/apache/sling/hc/samples/impl/AsyncHealthCheckSample.java?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/samples/src/main/java/org/apache/sling/hc/samples/impl/AsyncHealthCheckSample.java
(original)
+++
sling/trunk/bundles/extensions/healthcheck/samples/src/main/java/org/apache/sling/hc/samples/impl/AsyncHealthCheckSample.java
Wed Jul 30 13:23:12 2014
@@ -43,39 +43,23 @@ import org.slf4j.LoggerFactory;
@Property(name=HealthCheck.NAME),
@Property(name=HealthCheck.TAGS, unbounded=PropertyUnbounded.ARRAY),
@Property(name=HealthCheck.MBEAN_NAME),
-
- // Period *must* be a Long
- @Property(name="scheduler.period",
longValue=AsyncHealthCheckSample.PERIOD_SECONDS, propertyPrivate=true),
- // Concurrent=false avoids reentrant calls to run()
- @Property(name="scheduler.concurrent", boolValue=false)
+ @Property(name=HealthCheck.ASYNC_CRON_EXPRESSION)
+
})
-@Service(value={HealthCheck.class,Runnable.class})
-public class AsyncHealthCheckSample implements HealthCheck, Runnable {
+@Service
+public class AsyncHealthCheckSample implements HealthCheck {
- private final Logger log = LoggerFactory.getLogger(getClass());
- private final AtomicInteger counter = new AtomicInteger();
+ private final Logger log =
LoggerFactory.getLogger(AsyncHealthCheckSample.class);
+
+ // static because for factories, not always the same instance is returned
for
+ // the same service reference
+ private static final AtomicInteger counter = new AtomicInteger();
public static final int PERIOD_SECONDS = 5;
@Override
public Result execute() {
- final FormattingResultLog resultLog = new FormattingResultLog();
- final int value = counter.get();
- resultLog.debug("{} - counter value is {}", this, value);
- if(value % 2 != 0) {
- resultLog.warn("Counter value ({}) is not even", value);
- }
- return new Result(resultLog);
- }
-
- /** Called by the Sling scheduler, every {@link #SCHEDULER_PERIOD}
seconds, without
- * reentrant calls, as configured by our scheduler.* service properties.
- *
- * Simulates an expensive operation by waiting a random time up to twice
that period
- * before incrementing our counter.
- */
- @Override
- public void run() {
+
final long toWait = (long)(Math.random() * 2 * PERIOD_SECONDS);
log.info("{} - Waiting {} seconds to simulate an expensive
operation...", this, toWait);
try {
@@ -83,7 +67,17 @@ public class AsyncHealthCheckSample impl
} catch(InterruptedException iex) {
log.warn("Sleep interrupted", iex);
}
- counter.incrementAndGet();
- log.info("{} - counter set to {}", this, counter.get());
+
+ final int value = counter.incrementAndGet();
+ log.info("{} - counter set to {}", this, value);
+
+ final FormattingResultLog resultLog = new FormattingResultLog();
+
+ resultLog.debug("{} - counter value is {}", this, value);
+ if(value % 2 != 0) {
+ resultLog.warn("Counter value ({}) is not even", value);
+ }
+ return new Result(resultLog);
}
+
}
\ No newline at end of file
Modified:
sling/trunk/bundles/extensions/healthcheck/samples/src/main/resources/SLING-CONTENT/apps/hc/demo/install/org.apache.sling.hc.samples.impl.AsyncHealthCheckSample-1.json
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/healthcheck/samples/src/main/resources/SLING-CONTENT/apps/hc/demo/install/org.apache.sling.hc.samples.impl.AsyncHealthCheckSample-1.json?rev=1614655&r1=1614654&r2=1614655&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/healthcheck/samples/src/main/resources/SLING-CONTENT/apps/hc/demo/install/org.apache.sling.hc.samples.impl.AsyncHealthCheckSample-1.json
(original)
+++
sling/trunk/bundles/extensions/healthcheck/samples/src/main/resources/SLING-CONTENT/apps/hc/demo/install/org.apache.sling.hc.samples.impl.AsyncHealthCheckSample-1.json
Wed Jul 30 13:23:12 2014
@@ -2,5 +2,6 @@
"jcr:primaryType" : "sling:OsgiConfig",
"hc.name" : "Asynchronous Health Check sample",
"hc.tags" : [async],
- "hc.mbean.name" : "AsyncHealthCheckSample"
+ "hc.mbean.name" : "AsyncHealthCheckSample",
+ "hc.async.cronExpression" : "*/20 * * * * ?"
}
